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| LM2745MTCX Datasheet, PDF (26/37 Pages) Texas Instruments – LM2745 / LM2748 Synchronous Buck Controller with Pre-Bias Startup, and Optional Clock | |||
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LM2745, LM2748
SNOSAL2E â APRIL 2005 â REVISED APRIL 2013
www.ti.com
IRMS_RIP = IOUT x D(1 - D)
Here n is the number of paralleled capacitors, ESR is the equivalent series resistance of each, and PCAP is the
dissipation in each. So for example if we use only one input capacitor of 24 mâ¦.
(1.924A)2 x 24 m:
PCAP =
12
PCAP = 88.8 mW
Output Inductor Loss (PIND)
PIND = I2OUT x DCR
where DCR is the DC resistance. Therefore, for example
PIND = (4A)2 x 11 mâ¦
PIND = 176 mW
Total System Efficiency
PTOTAL = PFET + PIC + PGATE + PCAP + PIND
POUT
K = POUT + PTOTAL x 100%
4.8W
K = 4.8W + 0.6W = 89%
Example Circuits
VCC = VIN= 3.3V
RCC
RPULL-UP
CCC
Clk
CClk
RFADJ
CSS
D1
CBOOT
VCC LM2745
SD
PWGD
FREQ/SYNC
SS/TRACK
SGND
EAO
HG
BOOT
ISEN
LG
PGND
PGND
FB
CC2
CC1
RC1
Q1
RCS
L1
RC2
CC3
+ CIN1,2
VOUT = 1.8V@2A
RFB2
+
CO1,2
RFB1
Figure 33. 3.3V to 1.8V @ 2A, fSW = 300 kHz
26
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Product Folder Links: LM2745 LM2748
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